Learning Python - My First Program

I have tried to learn some coding before but didn't have enough time/ambition to do so. This year, I started learning Python again and I am taking it more seriously. I am determined to learn it and do something "useful" with it. One of the courses I am taking is An Introduction to Interactive Programming in Python on Coursera and the code below is for our first Miniproject (Rock-paper-scissors-lizard-Spock). Any feedback is appreciated.

# My first program
# Rock-paper-scissors-lizard-Spock

import random
import math

def name_to_number(name): # converts name to number
    if name == "rock":
        return "0"  
    elif name == "Spock":
        return "1"
    elif name == "paper":
        return "2"
    elif name == "lizard":
        return "3"
    elif name == "scissors":
        return "4"
    else:
        print "Please choose one of these : rock, Spock, paper, lizard, scissors."

def number_to_name(number): # converts number to a name
    if number == 0:
        return "rock"
   
    elif number == 1:
        return "Spock"
       
    elif number == 2:
        return "paper"
       
    elif number == 3:
        return "lizard"
       
    elif number == 4:
        return "scissors"
   
def rpsls(player_choice):
   
    print "New game!"
   
    print ""
   
    print "Player chooses " + player_choice
   
    comp_number = int(random.randrange(0 , 5)) # computes random guess for comp_number
   
    comp_choice = number_to_name(comp_number)
   
    player_number = int(name_to_number(player_choice))
       
    print "Computer chooses", comp_choice

    num = int((comp_number - player_number) % 5) # computes difference of comp_number and player_number modulo five
   
    if (num == 1) or (num == 2) or (num == - 1) or (num == - 2):
       
        print "Computer wins!"
       
    elif (num == 3) or (num == 4)or (num == - 3) or (num == - 4):
       
        print "Player wins!"
       
    elif (num == 0):
       
        print "Player and computer tie!"

rpsls("rock")
rpsls("Spock")
rpsls("paper")
rpsls("lizard")
rpsls("scissors")